Rheostat



March 26, 1929, Q W ELMWALL 1,706,570

RHEOSTAT Filed May 1, 1926 ANH/W57 Patented Mar. 26, `1929.

UNITED STATES PATENT OFFICE.

GUSTAVE WALFRID ELMWALL, F NEW YORK, N. Y.

RHEOSTAT.

Application filed May 1, 1926. Serial No. 105,973.

This invention relates to electrical apparatus and more especially to rheostats.

It is the primary object of this invention to provide means whereby the regulation of lamps, motors, medical and other appliances commonly attached to standard electrical lamp socketsV and plugging outlets, may be accomplished with added facility and 1mprovedsimplicity. y v

Appliances operated by electricity, particularly those ot' theportahle or household type, are commonly supplied with current from a convenient lamp socket or 'from plugging receptacles mounted in the walls or lloor. Sockets and receptaclesof this character are generally supplied with either a simple switch "or connected directly across the supply wires without a control device of any sort in their circuit thus appliances used were heretofore generally thrown directly on at full voltagel and have so operated until altogether cut oli'. ln the case ot fans and sonic other devices cumbersome rheostats f have been mounted in the machine base but the need oil? meeting` lower prices of competitors has led to this practice ybeing neglected even in these particular instances while naturL lly such rheostats helped not at all to control other appliances usedby the same owner. It is the particular purpose of this invention to provide a control device capable of being readily attached to sockets and receptacles of the character described in such -manner that .it will be interposed in the circuit supplying the appliance being used and can bemanipulated to control the connected appliance with any desired degree of accuracy or latitude.

Another purpose 'ot the herein (.isclosed invention lies in the provision. oli a control device capable of being used after vthe manner described above and also having such simplicityot1 structure and accessibility of parts that its operation and repair will be at once easy and quick so that the device may serve 1iroinptly and for a maximum portion ,oit its entire lite without'wasted time awaiting repairs and adjustments.

`It is also the purpose of this `invention to furnish a control. device for the purposes described above having means as a part thereoi' 'for engaging beth the socket or receptacle from which the electricity is to be drawn and the connection device orf the appliance to be operated by the current supplied so that it may be interchangeably used without tools or specialized knowledge on the part of the user.

The device herein used to illustrate an embodiment of my invention is most particularly suited to form a part of the controls for medical apparatus of the character described in Patent Number 1,545,413 issued July 7, 1925, and entitled Eleetrotherapeutic glove and for other apparatus of like character being suited to obtain the close regulation and accurate easy control essential to treatments of the human body and oi like delicate character operations.

A further object of my invention lies in so embodying my invention that the parts cooperating to provide the whole unitary means may be readily replaced when worn or when it is desired to obtain other current capacities, degrees or ranges of control.

Referring to the drawings and to the `embodiment oit my invention shown therein for purposes of illustration:

Fig.,1 is a front elevation of the complete device. l

Fig. 2 is a cross sectional view taken on line 2--2 of Fig. 1.

Fig. 3 is a vertical cross section of the device shown in the preceding figures but taken in a plane at right angles to that of Big. 2.

Fig. 4 is also cross sectional oi" the device shown and is taken on line 4 4 et Fig. 1 looking downward as indicated by the arrows.

In the main the device shown consists ot an attachii'ient plug or top portion 1l), an

` attachment socket or receptacle tor the appliance to be controlled as shown in bottom pertien 20rcsistance units 30, a control si'ler 40, and a protectivecasing or shield 50.

In. detail; Thetop portion consists of a moulded insulating body 11 having an enlarged grooved rim 12, the resistance unit Vholding' lugs 14 and suitable recesses and openings for the threadedcontact 15 which has a downwardly extending connection 15 joining it with the resistance unit connection ring 15b and for the central contact` V1G held by the screw 153iL and joined by the connection 161 to the other resistance unit connection ring` 16C. Portion 10 is also recessed and bored to receive the heads 41a of the slider rods 41 which will be further described.

The bottom portion consists also of an insulating body 21 having a rim grooved at Q2 in a similar fashion to the rim on the upper portion. Portion 2O is recessed and bored to hold socket contact or shell 23 provided with a threaded extension into which one of slider rods Lll screws, while the central contact 24 and its threaded extension 2li engage the other slider rod andere likewise held and supported by the body 2l.

rl`he resistance units shown consist of an insulating tube upon the surface of which is wound resistance wire 30". The units here shown are of sehn-circular cross section having a liattened side but it will be understood that rectangular or round resistance tubes such as are well known to those skilled in the art, may be employed and that all of these may be held by lugs 14 on portion l1 and lugs 25 on portion 20 when in place. The terminals of resistance wire 30" are preferably led outward at the tube ends and contact with rings 15b and 16u so that connection is made through the attacln'nent portion contacts with the current supply source. The resistance wires are thus normally connected one to each of the supply wires but are insulated from each other and from appliance connections by bodies ll and 21. It will be understood that for certain purposes the outer ends of the resistance coils may be joined together to form a potentiometer or the like well known to the art.

The slider fl() consists of a cross bar of Vinsulating material 42 terminating in linger pieces 42 and bored to slide over slider rods 4l; cross bar t2 is also provided with openings 42D through which spring wire contacts 4:3 extend to serve as brush contacts with rods l1 and at the outer ends to serve as mountings for contact wheels lll riding over and making Contact with resistance wires 30" of the resistance units 30 already described. Thus it will be seen that contact wires 43 serve to carry the current from the resistance units to the contact rods 41 which in turn conduct it to the two contacts in the appliance connection socket through extensions 23 and Q/Fvpreviously mentioned. It will be noted that slider l() is moved downward and contact made farther down the resistance units more resistance will be introduced into `thecircnit and the current supplied to the appliance will be further reduced, while as the slider is moved upward so will the current be increased and, if the appliance controlled be a lamp, so will the illumination increase.

rIhe shield consists of two semi-cylindrical sections preferably of heavy screen or perforated metal and having their upper and lower edges turned inward at the ends as at 5l to engage the grooved rims of portions l() and 2O for support. Adjacent these turned in edge an indentation or groove 52 serves to seat and position clamping rings 54 of spring wire or the like which securely clamp the parts of the shield in place so that it forms a protection against accidental contact with any of the live parts or with the hot resistance wires.

The operation of the device has already been indica-ted while the rigidity of the whole; seeing that resistance units 30 are sccurely held clamped by, and in turn support and space, the end portions held against separation by slider rods ell; will be manifest. It will be clear that the device capable of a large variety of uses and that while connection devices of the so called Edison type have been shown, knife or other type connectors may also be used and that many other such modifications are well within the skill of persons familiar with electrical apparatus of the type set forth. lfilani'ifestly many such changes and modiiications are well within the scope of my invention and the spirit of the appended claims.

IVhat I claim is:

l. In a current regulating device, moulded end members provided with lugs and with terminal and terminal conductor recesses, resistance units of half circuar cross section provided with end recesses adapted to engage said lugs and with a resistance conductor having terminals projecting thereon lto engage certain of the terminal conductors mounted in said end member recesses, a resistance contact slider provided with means adjustably engaging the flat side of said resistance units and the resistance conductor thereon, clamp rods engaging said end members and terminal conductors mounted in said end member recesses, and a two part guard shield engaging the exterior of said end members and clamp rings for securing the same thereon, said end members supported thereby and therethrough spaced from said units and conducting parts.

2. In rheostats of the socket attachment type, moulded insulating end members having male and female socket and plug engagement elements mounted therein and thereon, said members also provided with mounting elements capable of simultaneous engagement with the two ends of a resistance mounting and insulating tube and with the resistance wire thereon, a plurality of metallic conductors mounted in and on said insulating members toform electrical connection means thereover and therethrough while at the same time providing connection'and mounting for rods extending between said insulating members to secure the same upon the ends of removable and interchangeable resistance units mounted therebetween, said insulating members providing mounting for al guard shield clamped thereon, said resistance units having resistance wire wound thereupon and having externally exposed portions thereof on their outer surface, a connection slider mounted upon said rods, sliding thereover and project-ing between said resistance units, said slider having spring pressed connection members projecting at its sides engaged with said rods and contacting With the eX- posed portion of the resistance Wire on a iiattened portion of said interchangeable resistance units when mounted in the rheostat, said rods and shield removable to permit removal and exchange of said resistance units when desired,

3. In rheostats ot' the socket attachment type, an upperI insulating member mounting a male attachment plug` projecting from the upper face thereof and resistance connection pm connectors projecting Ytrom the under surface thereof, a lower insulating member mounting upon its lower surface, a female attachment plug receptacle and upon its upper surface resistance pin connectors electrically joined to the Contact surfaces of said attachment plug receptacle, interchangeable resistance unit-s having recesses in their ends so that said units may be inserted between said insulating members and upon said pins and by 'said insertion Will be electrically connected thereto and mechanically joined there- With so that insertion and aliixing of slider rods will join the Whole in self supporting structure, a plurality of slider rods extending between the said insulating members for the purposes set forth and tomount'an adjustment slider contacting With the surfaces of resistance units, and a guard shield clamping over the said members and supported thereby to insulate the same against acciden tal Contact 'from Without.

Signed this 3rd day ot' April, 1926, at New York, N. Y.

GUSTI/NYE WALFRD ELMVVALL. 

